Assisted electric brake devices characteristically require a form of transmission that allows the angular movement of an electric motor to be converted into a linear movement in order to apply a force and displace one or several pistons in a hydraulic pressure generator such as a master cylinder.
Ball screw devices are generally considered for applications of this kind. However, the components of this kind of ball screw transmission device are very rigid under load and due to the numerous dimensional tolerances in the system, they do not allow the guide plane of the piston of the master cylinder to be adjusted in its bore to remain within narrow radial tolerances and allow the pressure-generating function to be guaranteed throughout a service life. The extent of the lateral constraints exerted by the piston on the bore and the reactive forces applied to the ball screw transmission cause premature wearing of the transmission and do not allow it to endure effectively and/or guarantee the reliability of the brake system.